Hi, I would like to have a simple application which delivers wms layers in scales/resolutions which are not the usual OSM/Google messy scales, but rather include 1:1000 000 / 1:500 000 / 1:250 000 / 1:100 000 / 1: 50 0000/ 1:10 000, 1: 5000 and 1:2,500. To make this even more difficult I need to do this in EPSG:25832 the european standard ETRS/ UTM zone 32 projected CRS with units of meters
As far as I have understood, this is fully dependant on the basemap resolutions. As this is pure mathematical I would like to show what I think I have learnt and wait for comments.... R = resolution S = scale as denominator IPU = OpenLayers.INCHES_PER_UNIT[units] = 39.3701 inches in a meter DPI = OpenLayers.DOTS_PER_INCH = 25.4 / 0.28 = 90.71428571428571 ( 1 inch = 25.4 mm / standardized pixel size of 0.28x0.28mm) this must be set in the application code "OpenLayers.DOTS_PER_INCH = 25.4 / 0.28" = 90.7142 otherwise, the scale factor would be 72 / 90.7143 = 0.7937. R= S / IPU * DPI using this formular, we are basically working out how many pixels there are in 1 meter of screen, to so find out how many pixels there are in 1000000 meters of screen we use... [Scale 1:1000 000] R = 1000000 / (39.2701 * 90.71428571428571) R =1000000 / 3562.359071428571260271 R = 280.712859077111976006937033 [Scale 1:500000] R = 500000 / (39.2701 * 90.71428571428571) R =500000 / 3562.359071428571260271 R = 140.356429538555988003468517 ...etc for the 1:250 000 / 1:100 000 ... What bothers me though, is that every EPSG code with units of meters will have the same resolutions. Is this correct? sources: http://geowebcache.org/docs/current/concepts/gridsets.html http://wiki.osgeo.org/wiki/WMS_Tiling_Client_Recommendation
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